Apparatus for producing accompanying music



Dec. l2, 1933. M. DREXI.

APPARATUS FOR PRODUCING ACCOMPANYING MUSIC Filed July 15. 1951 JNVENT'OB., www( Patented Dec. 12, 1933 APPARATUS 'FOR PRODUCING ACCOMPANYING MUSIC Martin Drexl, Kaldenkirchen, Germany Application July 15, 1931, Serial No. 550,976, and

in Germany October 17, 1929 i 7 Claims.

Itis known that, when singing or playing music near music instruments, the undamped harmonic resonance bodies of these instruments oscillate according to the actually produced sounds. It is also known to convert these mechanical oscillations into electrical sound waves and to reproduce same by a loudspeaker.

As compared herewith the invention relates to a method, in which a singing voiceis partly conducted into a microphone, and the undulating current produced therein, compels those resonance bodies of a series of differently tunedresonance bodies, for example steel tongues, which have a like or absolutely harmonic self vibration, to os- 1. cillate with the actual melody, produced by the singer. These sounds are then filtered, that is separated relative to one another and to suit the melody sound just rendered and formed into a clear chord and adapted in tone, that is are given the tone of a certain instrument, without a tone body being necessary as in the registers of an organ. This musical accompaniment is then, regulated as desired, rendered audible by a loudspeaker, besides which sound that portion of the voice of the singer sounds in full clearness and character, which has not passed through the microphone and the loudspeaker.

The arrangement for practically carrying out the idea of the invention will be hereinafter described with reference to the accompanying drawing, in which Fig. I shows diagrammatically the general arrangement. The singer sings from the point designated by X in a circle, behind the desk or switch table 1 into the threepole, strong primary microphone 2 and then switches the undulating current thus produced through the vcable 3, battery 4 and amplifier valves 5 into a soundproof box 6, arranged at any desired distance away. In this -box the chord producer is accommodated, which is shown in top plan view in Fig. II, in longitudinal section in Fig. III and in vertical section in Fig. IV. Figs. V and VI show in horizontal and vertical section a bell 13 serving as soundbody.

Figs. VII and VIII show a frame 16, having a diaphragm of sheet brass, stretched hide or thin wood. Figs. IX and X show in top plan view and in section a violin as sound body.

'Ihe chord producer (Figs. II-IV) is formed by electromagnets 8, which are surrounded by coils 9, which serve for the talking current coming from the primary microphone 2 and over the wide poles of which a thin reed comb 10, similar to the sound producer of a musical box, is arranged,

which is nxea with one longitudinal edge on the poles of the electromagnets 8, the plurality of tongues `ll of the other edge, which form like pole pieces, oscillating freely over the unlike pole ends of the magnets 8. A reed is provided` for each sound occurring during the singing or desired for the accompaniment. In the portion of the plate 10 not cut into tongues, but oscillating and serving for collecting" and mutually amplifying, refining or destroying the sounds coming from the tongues 11, the secondary microphones 12a, 12b, 12c, 12d 65 and 12e areY arranged, which can be switched in,

as desired, in the table 1, and from which the current,.containing the vibrations of the accompaniment, amplified as desired by the valves 5, passes to the'loudspeaker 7 at the side of the desk 70 of the singer.

This secondary current may however, for the purpose of giving timbre, be first Aconducted entirely or partially to the magnet 14 on the bell 13, to the magnet 17 on the frame 16 or to the 75 magnet 21 on the violin 19 provided with strings 20. of which one has a very deep self resonance sound, where it causes this resonance body to oscillate in the chords peculiar thereto and the music enriched by the secondary sounds peculiar to each resonance body, is caught by the microphones 15, 18, 22 and conducted to the loudspeaker 7.

This arrangement operates in the following mannerz- 85 The current coming from the primary microphone 2 causes all the steel tongues 11, which have a like or harmonic self vibration to that of the sound actually sung, to immediately vibrate strongly and continually, and these vibrations are therefore also propagated through their root into the collector plate 10 to the microphones 12a to 12e. As, however, for accompaniment only sounds are desired which lie below the voice pitch of the singer, the singer only switches in the secondary microphone 12e and perhaps also the microphone 12d, especially, when the ac` companiment is required for a womans voice, that is the contact points in which the reeds situated under the pitch of the melody have their root and cause the strongest vibrations, even if the higher sounding reeds vibrate slightly therewith.

In order that the musical sound exactly corresponding to that of the melody is not produced ,predominating toostrongly and drowning the voice, vit can be entirely damped in the loud speaker by conducting a portion of the talking current coming from the primary microphone 2 past the chord producer (Figs. II to IV) directly to the loudspeaker 'Z and there switching it inversely to -the musical sound current coming from the secondary microphone 12, so that the positive and negative impulses, corresponding to the melody soundV of the two currents, neutralize one another instead of amplifying one another, the desiredvpeculiar-accompaniment sounds of the music becoming thus audible together with the song coming directly through the air from the singer, which song can evidently be amplified by the loudspeaker and delivered.

If a singer desires to have covering higher sounds for his voice, if the same is too cold, he

merely switches in feebly the secondary microphone 12a, situated opposite the very high reeds.

If a diierent timbre is required than that of the steel reeds or of the collector plate 10, the current coming from the secondary microphone 12, is simply sent through one or several timbre colorers, switched in parallel or in series (Figs. V-X) so that diierent combinations are obtained. 'I'he sound of the chords comingl from the electromagnetically actuated wall of the bell 13, is purer` and more pleasant than the self resonance sound produced by striking, and the sounds of the Violin 19, produced without touching the strings, have a flageolet character from the lowest to the highest.

By means of this instrument it is possible to obtain an ample full and in itself satisfactory music and also an introduction and finish to the song, instead of an accompaniment for a song or to a single part instrument, by humming very softly into the microphone so that it is inaudible to the public, it being evidently possible to render the music much more varied, if two or more singers cooperate in front of the microphone.

1. An apparatus `for producing 'musical accompaniments, comprising in combination a battery, a circuit connected to said battery, a primary microphone in 'said circuit adapted to pick up the sound waves of the music to be accompanied and produce undulating current in said circuit, aloudspeaker connected to said microphone adapted to directly reproduce the sounds of the music to be accompanied, a chord producer Vconsisting of electromagnets surrounded by coils connectedwith said circuit adapted to receive said undulating current and of tongues extending from a common collector plate adapted to vibrate according to the excitation of said electromagnets to produce the accompaniment sounds, secondary microphones on said collector plateconnected with said circuit adapted to pick up'the sound waves produced by said tongues and supply same to said loudspeaker as musical I accompaniment tothe sound waves picked up by prising,r in combination with the loudspeaker, the

primary microphone, the circuit, the chord producer and the secondary microphones, means shunt connected with said circuitadapted lto conduct a portion of the current from said pri-` mary microphonepast said .chord producer to suppress the sounds of the accompanying music having the same. pitch 'as .that of themusi" to 'beaccompanied, an amplifier in said circuit between saidprimary microphone and said loudspeaker adapted 'to amplify the sound lwaves, of

. the "current yproduied` by said primary microphone on its passage to said loudspeaker, and a switchboard in said circuit adapted to switch the current fromk said secondary microphnes to said loudspeaker.

3. In an apparatus as speciiied in claim 1, the combination with the secondary microphones, the circuit )and the` chord producer, comprising tongues,connected with vsaid circuit for accentuating and preventing the sounding of certain of. said tongues, and a switch disc connected with said circuit adapted to control said means.

4. An apparatus as specified in claim 1, comprising in combination with the loudspeaker, the circuit and the secondary microphones, a magnet shuntv connected to said circuit adapted to receive current from said secondary microphones, means connected to said magnet for regulating the quantity of current supplied to said magnet, a bell carrying said magnet adapted to be vibrated by the current passing through said magnet to regulate the timbre of the musical sound produced, a further microphone on said bell connected up to said circuit adapted to take up the vibrations produced in said bell and supply same to said loudspeaker through said circuit.

5. An apparatus as specified in claim 1, comprising in combination with the loudspeaker, the circuit and the secondary microphones, a magnet shunt connected to said circuit adapted to receive current from said secondary microphones, 105 means connected to said magnet for regulating the quantity of current supplied to said magnet,

a sheet metal diaphragm carrying said magnet adapted to be vibrated by the current passing through said magnet to regulate the timbre of 1 10 the musical sound produced, a further microphone on sa'id sheet metal diaphragm connected up to said circuit `adapted to take up the Vibrations produced in said sheet metal diaphragm and supply same to said loudspeaker through 1,15 said circuit.

6. An apparatus as speciiied in claim l, comprising in combination with the loudspeaker, the circuit and the secondary microphones, a magnet shunt connected to said circuit adapted to receive current from said secondary microphones, meansconnected to said magnet for regulating the quantity of current supplied to ,said'magnetV a wooden diaphragm carrying said magnet adapt-l ed to be vibrated by the current passing through 125. said magnet to regulate the timbre of the musical sound produced, a further microphone on said wooden diaphragm connected up to said circuit adapted to takeup the vibrations produced in said wooden diaphragm; and supply same to said loudspeaker through said circuit.

7. An apparatus as speciiied in claim 1, com` prising in combination with the loudspeaker, the circuit and the secondary microphones, a magnet shunt connected to said circuit adapted to' 135 receive current from said secondary microphones,'means connected to said magnet for regulating the quantity of current supplied to said magnet, a, violin carrying` said magnet adapted A 

